<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .box-container{
            position: relative;
        }
        .box{
            width: 500px;
            height: 10px;
            background-color: #b5bdc7;
            margin-top: 50vh;
            margin-left: 50vw;
            position: absolute;
            overflow: hidden;
        }

        .box::before{
            content: '';
            width: 500px;
            height: 10px;
            background-color: #00b4db;
            position: absolute;
            animation-name: shuizhu;
            animation-duration: 5s;
            animation-iteration-count: 5;
            left: 0;
            transform: translateX(-100%);
        }

        @keyframes shuizhu {
            0%{
               left: 0;
            }
            90%{
                opacity: 1;
            }
            100%{
                left: 100%;
                opacity: 0;
            }
        }
    </style>
</head>
<body>

<div class="box-container">
    <div class="box"></div>
</div>
</body>
</html>